1. Field of the Invention
The present invention relates to steering wheel and airbag assemblies, as well as their interfaces on motor vehicles. More specifically, the invention relates to a novel steering wheel and airbag assembly that eliminates the gap between the driver's side airbag cover and the steering wheel.
2. Description of Related Art
Steering wheels are universally used as an essential component of a motor vehicle. Through the steering wheel, the vehicle driver steers and controls the vehicle. The steering wheel controls the vehicle's steering assembly such that the vehicle driver is able to control the vehicle's movement and direction by simply rotating the steering wheel.
Traditionally, a steering wheel includes two sections: a center portion (often called a “center” or a “body”) that is coupled to an outer rim (sometimes called a “rim”). The outer rim encircles the center portion and is designed to receive the driver's hands. Usually, the steering wheel is designed such that the driver will guide the vehicle by pulling and/or turning the outer rim.
The center portion is generally mounted to a steering column. The steering column extends from the vehicle's dashboard and is used to couple the steering wheel to the steering assembly. Gears, shafts, mechanical linkages, electrical linkages, or other similar features are then added to the steering column. Upon rotation of the steering wheel, these gears and/or other features engage the steering assembly and cause the vehicle to turn or move in the desired direction.
Additionally, because most vehicles possess a horn, most steering wheels are now designed to include a horn assembly. The horn assembly is positioned on the center portion and is capable of producing a sound. The horn assembly is generally designed such that if a driver or other vehicle occupant presses inwardly on a horn switch and/or the center portion, the horn assembly will actuate and a sound will be produced. Preferably, such horn assemblies are spring-loaded such that a vehicle occupant may actuate the horn assembly by pressing and/or touching the horn switch and/or the center portion with a single hand.
Recently steering wheel designs have further been affected by automotive design trends that include the incorporation of the switches onto the steering wheel. For example, many steering wheels now include speed control switches, cruise-control switches, radio switches, audio switches, telephone switches, global-positioning satellite switches, as well as other types of switches. Other steering wheels have been made to include decorative and/or functional features such as lights, message boards, gauges, foam, spokes, spoke covers, decorative spoke finishers, and the like.
Perhaps the most sweeping change in the design of steering wheels is the inclusion of inflatable safety restraints or airbags within the center portion. Airbags are designed to inflate to prevent the vehicle occupant from harmfully impacting the steering wheel, the steering column, the windshield, the dashboard, or other portions of the vehicle interior during a crash.
The airbag is generally housed within an airbag module that has been added to the center portion. An airbag cover that goes over the module is also added. The cover is usually made of a rigid plastic material and is made to open by the pressure from the deploying airbag. During deployment of the airbag, it is preferable to retain the airbag cover in at least partial attachment to the vehicle to prevent the airbag cover from flying loose in the passenger compartment. If the airbag cover were allowed to detach and freely move into the passenger compartment, it could cause injury to a passenger.
The airbag is generally linked to a control system that controls its deployment when an collision occurs. The control system is often called an electronic control system or “ECU”. The ECU includes a sensor that continuously monitors the acceleration and deceleration of the vehicle. This information is sent to a processor which processes it using an algorithm to determine if a deceleration experienced by the vehicle is a collision or not. If this accelerometer measures an abnormal deceleration, such as one caused by a collision event, it triggers the airbag inflator.
When the ECU determines, based on a set of pre-determined criteria, that the vehicle is experiencing a collision, the ECU transmits an electrical current to an initiator assembly. The initiator assembly is in turn connected to an inflator that is coupled to the airbag module. The initiator activates the inflator. An inflator is generally a gas generator that typically uses a compressed or liquefied gas or mixture of gases, a solid fuel, or some combination of the two, to rapidly generate a large volume of inflation gas. This inflation gas is then channeled, often through a segment of specialized tubing called a gas guide, to the airbag. The gas inflates the airbag, allowing it to absorb the impact of the vehicle occupants and thus protecting them from harmful impact against the vehicle interior.
As experience with the manufacturer and use of airbags has progressed, the engineering challenges in their design, construction, and use have become better understood. For example, most steering wheels are currently designed such that there is a gap or opening that separates the airbag module from the adjoining section of the steering wheel. The reason for this gap is that steering wheel manufacturers believe that in order to allow the horn switch and/or the center portion to depress during actuation of the horn assembly, the horn assembly must be completely separated from the airbag module. As a result, an opening is added to the steering wheel to achieve the desired separation.
Unfortunately, constructing a steering wheel such that there is a gap positioned between the airbag module and the other portions of the steering wheel significantly raises the manufacturer's overall production costs. By requiring a gap to surround the airbag module, the overall complexity and sophistication of the steering wheel is greatly increased. Accordingly, manufacturers are required to expend additional time, resources, and skill in assembling, installing, and testing the steering wheel units. The significance of such a cost increase cannot be over-emphasized because in the highly competitive automobile industry, even slight increases in production costs can greatly influence the overall profit margin on a mass-produced vehicle.
Moreover, including a gap on a steering wheel has a further limitation in that over the life of the vehicle, containments such as dirt, dust, moisture, and the like tend to collect and accumulate within the steering wheel gap. This accumulation of dirt makes the steering wheel undesirable and visually unappealing to most consumers. As a result, the overall satisfaction and enjoyment associated with driving and/or owning the vehicle will be greatly diminished.
In addition, placing a gap on the steering wheel is very inviting to curious children and others that like to poke, pick, scratch, or otherwise tamper with the steering wheel. Like the accumulation of dirt discussed above, such poking will, over time, deteriorate the visual appearance of the steering wheel and reduce the vehicle's overall desirability.
Current automotive industries continue to increase the requirement for improved cosmetic and appearance of steering wheel to airbag fist to compete in the market, thus requiring closely held gaps and tolerances of mating surfaces. Accordingly, there is a need in the art for a novel steering wheel that addresses and/or solves one or more of the above-listed problems. Such a device is disclosed herein.